The trio came forward voluntarily to police during an evening of activity by officers in Colchester, who are continuing their investigation into Mr Attfield’s death.

Detective Chief Inspector Simon Werrett said: “We spoke to a number of people in the town last night and we will now be assessing that information to see if it can assist us in taking the investigation forward.

“The three people pictured in CCTV images 5 and 5a also identified themselves to officers and have accounted for their movements and I would like to thank them for their assistance. I am now very keen to trace a woman who is seen in image 7 at 12.36am on Saturday March 29 and then again with a man in image 14 at 2.19am.

“I would urge these two people to come forward or if anyone recognises them I would ask them to get in touch with the enquiry team.”

Detectives are continuing to form a more detailed account of Mr Attfield’s movements between the evening of Friday, March 28 and the time he was found in Lower Castle Park just before 6am on Saturday, March 29, with more than 100 stab wounds.

He had died at the scene a short time after he was discovered.

A total of six people caught on CCTV walking through Lower Castle Park late on March 28 and into the early hours of March 29 have now been identified and eliminated from enquiries. A further 17 people have yet to come forward.

Officers are also still trying to trace a couple who were seen sitting on a bench in Lower Castle Park close to the lake at 11.30pm on the Friday.